In Austria, electricity production and consumption from household PV-installations in the private sector has just been possible for single-family homes so far. A change in law shall now provide the possibility of electricity consumption from communal PV-installations for tenants in multi-apartment buildings too. This raises the question, how the tenants' annual electricity costs are influenced by taking an optimal PV-installation (according to different load profiles) and, if required, an optimal storage, into account. In the course of this thesis optimal PV- and storage capacities, according costs or revenues as well as grid- or self-consumption rates are calculated for different case studies. Therefore an optimization-model is developed in Matlab, which identifies, on the basis of solar radiation for the location of Vienna, the optimal PV- and storage capacities for a multi-apartment building containing ten flats. The optimal capacities of PV-installations and storages do strongly depend on the inhabitants' requirements concerning self-consumption rates or cost reduction. To be able to investigate different goals, two opposite target functions - minimal cost and maximum self-consumption - are merged via a multi-objective optimization approach. Calculations are conducted for single flats as well as for the whole building considered as total load. Results show, that the concept of PV-installations and storages for multi-apartment buildings is right on the border of profitability in case of Austrian electricity prices. With German electricity prices however, PV-installations and storages are already highly profitable due to the higher quantity-dependent electricity price. Results also show, that dynamic allocation of produced electricity (multi-apartment building considered as total load) lead to more convenient results concerning profitability than static allocation (consideration of single flats' load profiles). This effect arises from synergy-effects between different load profiles. Furthermore sensitivity analyses are conducted to show how sensitive profitability is to prices for feed-in of surplus energy, weighted average cost of capital and storages' specific investment costs. The concept of PV-installations for tenants being first implemented in Austria should consider dynamic allocation of electricity right away to be able to achieve the best results possible. Nevertheless the development of new solutions and better business-models, which allow electricity trade between apartments in different buildings as well as the integration of electric vehicles' charging stations, must not be neglected.